shoreline detection capability of cosmo skymed and high resolution multispectral images

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Modelling of total suspended particulates in Malaysian coastal waters using remote sensing techniques

This study focused on environmental remote sensing with the objective of constructing a remote sensing algorithm to determine Total Suspended Particulate (TSP) concentrations in Malaysian coastal surface waters. Other objectives included coral reef mapping and production of quantitative map of [TSP] using the remote sensing algorithm at the study area which was Tanjung Rhu, located northeast of Pulau Langkawi, Peninsular Malaysia. Measured [TSP] varied from 93.92 ± 50.10 mg/L to 148.65 ± 45.39 mg/L. The biogeographic distribution of the reef in Tanjung Rhu was mapped and the hermatypic coral species was identified taxonomically. Results were compared to a control site, Teluk Datai located northwest of Pulau Langkawi. There were 37 coral species in Tanjung Rhu and 76 species in Teluk Datai. The Jaccard's score was 27% indicating that the two reefs were quite diverse in their coral compositions. The development of a remote sensing algorithm is deemed necessary to provide a synoptic view of the potential problem within the coastal waters due to the early coastal development in Tanjung Rhu. Sedimentation studies showed sediment fractions were mainly biogenic materials and lithified sediments. Sediment fallout rates in Tanjung Rhu were 1,403.48 ± 125.60 g/m2/day (dry season) and 6,550.77 ± 641.43 g/m2/day (wet season). In Teluk Datai the sediment fallout rates were 1,532.99 ± 201.81 g/m2/day (dry season) and 12,446.45 ± 237.81 g/m2/day (wet season). The remote sensing algorithm, Suspended Particulate Algorithm for Coastal Remote Sensing (SPACoRS) developed from a modified Simple Radiative Transfer Model is defined as [TSP] (mg/L) = 0.6668e4 .3892x , where x represents (Rrs-toaTM31RrstoaTM2) ratio. SPACoRS is designed to determine [TSP] of 30 - 275 mg/L with primary material of TSP having high backscattering and low absorbance values. Sensitivity of SP ACoRS to produce higher accuracies was limited to TSP ~ 15Omg/L. SP ACoRS' s accuracy using Landsat Thematic Mapper data was 66%

Evaluation of riverbank erosion based on mangrove boundary changes identification using multi-temporal satellite imagery

Evaluating riverbank erosion in mangrove forests is dynamic and challenging because of the complex environment that is exposed to tidal and sedimentation factor. Besides, assessing riverbank erosion in this environment requires a technique that reduces dependency on tidal and sedimentation without affecting the quality of the assessment. Hence, this study evaluated riverbank erosion based on mangrove boundary changes using multi-temporal satellite images comprising Quickbird, WorldView-2 and Pleiades-1B. The first objective of this study is to determine mangrove boundary shifting and its long-term impact towards riverbank features followed by validating the mangrove boundary shifting of satellite imagery with field measurement data, which comprise Real Time Kinematic-Global Positioning System (RTK-GPS). Next, the study assessed the rates of changes o f the riverbank erosion and accretion and the final objective developing a riverbank erosion prediction model. In this study, a change detection technique was used to identify the mangrove boundary changes of Kilim River at different timelines. The extracted mangrove boundary from satellite images for the years 2005, 2012 and 2017 were used to identify changes in the riverbank features such as line shifting, river width, erosion, and accretion. Subsequently, a vector image overlay was used to determine the mangrove boundary shifting for the corresponding years and evaluate the erosion and accretion rates using symmetrical difference and erase tool in ArcGIS software. Sequentially, Root Mean Square Error (RMSE) analysis validated the accuracy of image geo- referencing process while residual analysis was employed to validate the accuracy between satellite imagery and field measurement data comprising RTK-GPS and erosion pin data. Then, line buffering and kernel density analysis were used to develop a riverbank erosion prediction model based on three parameters, namely distance of erosion, area of erosion and direction of shifted mangrove boundary. The initial findings of this study showed that the mangrove boundary changes shifted backwards in the opposite direction from the river and the range of shifting was different according to the intensity o f boat traffic. One of the findings showed that the increasing rates of riverbank erosion ranged from 11302.019 square meters in the first epoch to 15674.721 square meters in the second epoch. Another finding illustrated the riverbank erosion prediction model which displayed several areas such as Sections A, B, I and L which are potentially facing serious riverbank erosion problems in the future in comparison to Sections C, D, E, F, G, H and K. The final finding discussed data validation between Pleiades-1B and GPS-RTK which recorded 0.305 of the r-square value whereas 0.477 was recorded as the r-square value for both Pleiades-1B and the erosion pin. The other validation comprised the second epoch of satellite image (WorldView-2 and Pleiades- 1B) and the erosion pin data which revealed the r-square of 0.9347 and showed the strong relationship between both data. As a conclusion, the findings have shown that the evaluation of the riverbank erosion based on mangrove boundary changes using multi-temporal satellite images is capable o f assisting stakeholders including the Langkawi Development Authority (LADA), Department of Irrigation and Drainage Malaysia (DID) and Marine Department Malaysia to have in-depth understanding of riverbank erosion issue that would enable them to prepare a mitigation plan in the future

Celebrating 25 Years of World Wetlands Day

The purpose of this Special Issue is to celebrate 25 years of “World Wetlands Day”. There is no other ecosystem that has its very own Ramsar Convention or such a challenge impacting ecosystem sustainability. Papers for this Special Issue provide an overview of wetland status and function within different regions of the world. The papers in this Special Issue of Land consist of three review papers, ten research articles and one perspective paper. Edward Maltby’s review paper provides us with an overview of the paradigm shift of how we value and assess wetlands over time. Ballut-Dajud et al. provide us with a worldwide perspective on factors affecting wetland loss. Finally, Jan Vymazal provides us with a historical overview of the development of water quality treatment wetlands in Europe and North America. The research papers can be grouped into four groups: 1) use of remote sensing to analyze stability and dynamic factors affecting wetlands; 2) factors affecting the wetlands’ ability to store carbon; 3) assessment of wetlands effect on water quality; and 4) understanding historical use and value of wetlands, farmer’s attitudes about wetland management, and how we can value wetland ecosystem services. Finally, Bryzek et al. remind us that, as wetland researchers and managers, we should minimize damage to wetlands even through field monitoring work

Estimating estuarine suspended sediment concentration through spectral indices and band ratios derived from Sentinel-2 data: a case of Umzimvubu Estuary, South Africa

The current study was aimed at evaluating the reliability and efficacy of selected remote sensing band ratios and indices in accurately estimating the spatial patterns of suspended sediment concentration level in Umzimvubu Estuary, Eastern Cape, South Africa. Sentinel-2 imagery was acquired on the 29th of March 2022. Band reflectance values were extracted from Sentinel -2 imagery, and laboratory measurements of suspended sediment concentration were obtained from samples collected from fifty (50) sampling points in the estuary on the 29th of March 2022. Sentinel-2 imagery was then validated with the field data in estimating and mapping the suspended sediment concentration. Several remote sensing band ratios Red/(Green plus Near-Infrared), Near-Infrared/Green, Red plus Near-Infrared/Green, Blue(Green plus Red)/Blue and Green plus Near-Infrared)/Blue and indices, that is the Normalised Difference Turbidity Index (NDTI), Normalized Difference Suspended Sediment Index (NDSSI) and Normalized Suspended Material Index (NSMI)) were then used to predict the suspended sediment concentration from Sentinel-2 imagery. The accuracy of band ratios and indices was evaluated by correlating the prediction against the observed suspended sediment concentration from Sentinel-2 imagery. A total of 50 points were randomly surveyed in the Umzimvubu estuary for analyzing suspended sediment concentration. Results indicate that the Blue (Green plus Red)/Blue, the Green plus Near-Infrared)/Blue and NMSI performed well based on their R-squared. The Blue (Green plus Red)/Blue and Green + Near-Infrared)/Blue band ratios had 0.86 and 0, 94, respectively. While NSMI yielded an R-squared of 0,76 and RMSE of 19,2 mg/L. The results in the current study indicate that Sentinel-2 imagery can reliably estimate the concentration of suspended sediment level in the Umzimvubu Estuary using band ratios and indices.Thesis (MSc) -- Faculty of Science and Agriculture, 202

Estimating estuarine suspended sediment concentration through spectral indices and band ratios derived from Sentinel-2 data: a case of Umzimvubu Estuary, South Africa

The current study was aimed at evaluating the reliability and efficacy of selected remote sensing band ratios and indices in accurately estimating the spatial patterns of suspended sediment concentration level in Umzimvubu Estuary, Eastern Cape, South Africa. Sentinel-2 imagery was acquired on the 29th of March 2022. Band reflectance values were extracted from Sentinel -2 imagery, and laboratory measurements of suspended sediment concentration were obtained from samples collected from fifty (50) sampling points in the estuary on the 29th of March 2022. Sentinel-2 imagery was then validated with the field data in estimating and mapping the suspended sediment concentration. Several remote sensing band ratios Red/(Green plus Near-Infrared), Near-Infrared/Green, Red plus Near-Infrared/Green, Blue(Green plus Red)/Blue and Green plus Near-Infrared)/Blue and indices, that is the Normalised Difference Turbidity Index (NDTI), Normalized Difference Suspended Sediment Index (NDSSI) and Normalized Suspended Material Index (NSMI)) were then used to predict the suspended sediment concentration from Sentinel-2 imagery. The accuracy of band ratios and indices was evaluated by correlating the prediction against the observed suspended sediment concentration from Sentinel-2 imagery. A total of 50 points were randomly surveyed in the Umzimvubu estuary for analyzing suspended sediment concentration. Results indicate that the Blue (Green plus Red)/Blue, the Green plus Near-Infrared)/Blue and NMSI performed well based on their R-squared. The Blue (Green plus Red)/Blue and Green + Near-Infrared)/Blue band ratios had 0.86 and 0, 94, respectively. While NSMI yielded an R-squared of 0,76 and RMSE of 19,2 mg/L. The results in the current study indicate that Sentinel-2 imagery can reliably estimate the concentration of suspended sediment level in the Umzimvubu Estuary using band ratios and indices.Thesis (MSc) -- Faculty of Science and Agriculture, 202